Air-borne corner reflector



March 8, 1949. CHRQMAK 2,463,517

AIRBORNE CORNER REFLECTOR Filed- June 30, 1945 Qwem M LEON CHROMAK inrecording range,

Patented Mar. 8, 1949 UNITED STATES "PATENT orrica 6 Claims.

amended April 30, 1928; 370 0. G. 757) This invention relates to aballoon with an enclosed radar reflector.

More particularly, the illustrated embodiment of the invention is acombined collapsible balloon and radar corner reflector assembly whichis compact and which may be inflated by gas to operative condition. Aswill be understood, hydrogen or helium are suitable gases for inflatingthe baloon assembly. The reflector unit is completely enclosed withinthe balloon and is secured at spaced points about its inner periphery.The refiector may conveniently be made with three pieces of electricallyconductive material intersecting or cut so that their planes make rightangles with each other and all pass through a common geometrical centerto form eight sections. The conductive material may be elastic'knitted,woven, or other material naturally, or treated to render it, conductive,or thin metallic sheet material and the like.

Prior to these improvements, it was the practice to suspend a radarcorner reflector from a balloon prior to ascent. This prior constructioncreates a drag which importantly restricts the rate of ascent and thealtitude attained by units of convenient size. In addition to the windor air resistance, of prior constructions, the additional weight of aframe work for the reflector adds to the total drag.

The present improvements eliminate the drag caused by the use of aseparate suspended reflector unit and enables the use of a verylight-weight reflector. The reflector can be more fragile thanpreviously, as it is protected against weather by the rubber balloonstructure. It is held in operative position within the balloon by thegas pressure against the inside of the balloon.

While the invention is of paramount importance in ascending balloonassemblies, it may be navigation. In the former case, the weight of arain-soaked or ladened reflector adds to the drag of separate units andin the latter case the protection to the reflector afforded by theballoon multiplies its life several times. Upper wind velocities, i. e.,at elevations of from 30,000 to 40,000 yards, heretofore unobtainable,may be recorded by use of the present invention. With prior devices suchreadings could not be obtained because these heights were not attainedby the balloon and unit or at least not while it remained As will beunderstood, the balloon is made of electrically non-conducting material.

The device being collapsible can be packed into a small space. Theelasticity of the supports and/or the reflector unit itself provides forthe usual expansion of the ascending balloon. The unit does not cut offthe balloon into isolated sections and accordingly it may be filled withgas through a single port. I prefer to seal the balloon after thereflector unit is secured in position. The seal may be a separate pieceas illustrated, or may include the intake port.

A typical baloon will be about six (6) feet in diameter, although a suchsmaller or larger one may be used. The points of the reflector suriacesare joined by rubber bands, as by spot vuloanization. The use of rubberbands or elastic reflector surfaces is to allow for the usual expansionof a rubber balloon as it attains great height with the resulting lowatmospheric pressure.

An object of this invention is to provide a combined balloon andenclosed radar reflector unit. 1

Another object is to provide a unitary structure of light weight whichprotects the reflector unit against the weather and increases the rateof ascent and altiude attained for a given amount of gas or size of theunit.

Another object is to provide an enclosed .radar corner reflector withmeans to compensate for the lower atmospheric pressure at highaltitudes.

These and other objects of invention will be manifest from aconsideration of the description, claims and drawings, in which thefigure is a sectional view of the inflated balloon and enclosed radarreflector in operative position ready to be launched.

Referring to the drawing, a 3 or 6 foot diameter or other size balloonit! which may be rubber, paper or cloth treated to render it non-porous,has a gas intake extension or port it which may be sealed by anconvenient means, such as cord l2. The reflector device may be assembledin position by inserting it through an opening which is later closed asby a vulcanized seal E3.

The reflector unit is collapsible and in operative position forms threeintersecting surfaces, l4, l5, and i6, at substantially right angles toeach other. The planes of each of the surfaces has a common geometricalcenter at H and, as

\ will be understood, form eight (8) three-sided or trihedral sections.If the figure be turned in either direction about its vertical axis theradar corner reflector portion will be the same as shown. The surfacesM, l5 and It may be sewn or otherwise joined together. The six points ofthe unit are each connected to rubber bands, such as l8, I9, 20 and 2|which in turn are spot vulcanized or otherwise connected to the insideof the bal- Additional rubber bands loon as at 22, 23, 24, 25. andconnections may be used if desired.

The reflector unit may vary from the illustrated embodiment. Forexample, the sides may be curved instead of straight, the surfaces maybe elastic knit goods, with cords substituted for the rubber bands, andother substitutions within the skill of those trained in the art may bemade.

It will be seen that I have eliminated the drags oi. separate reflectorunits and the weight of their frame structure and have provided a meansfor attaining great height with a higher rate of ascent than possiblewith prior devices of like size. I have done this without impairing theefflciency of the reflector unit.

Having described my invention in a preferred embodiment, I wish it to beunderstood that any radar reflector such as might be used in radio rangedetection work with a fixed or ascending balloon is contemplated to bewithin the scope oi the present improvements.

This invention may be made or used by or for the Government of theUnited States for governmental purposes without the payment to me of anyroyalties thereon or therefor.

What I claim is:

1. In combination, a collapsible inflatable windsounding balloon, anenclosed collapsible electrically conductive network, means including amultiplicity of elastic supports for securing said network in operativeposition when the balloon is inflated, said supports being provided toyield with the expansion of the balloon as it attains hi h altitudes oris subjected to high internal pressure, whereby said network is heldrigidly in operative position.

2. In combination, a collapsible windsounding balloon, an enclosedcollapsible electrically conductive network, said network having eightthreesided sections the sides of which are at substantially right anglesto each other and form six points in all, elastic securing meansindividually connected to the outer ends of said sections and to theinside of the windsounding balloon.

'3. In a radiant energy reflection system a selfcontained unitcomprising a collapsible inflatable windsounding balloon having a gasintake port and containing therein an enclosed collapsible electricallyconductive network comprising eight three-sided sections substantiallymounted mutually perpendicular to one another forming six points eachsecured by elastic means to the in- 4 side of said balloon, said formednetwork reflecting impinging ultra short electromagnetic waves towardtheir source.

4. An airborne reflector for ultra short mac- 5 netic waves comprising aprotective, flexible, balloon, an electrically conductive, collapsible,multiplanar reflector network yieldably secured within said "balloon,the aforementioned network being held in an uncollapsed position whenthe balloon is inflated, whereby impinging ultra short magnetic wavesare reflected towards their source.

5. An airborne reflector for ultra short magnetic waves comprising anunmanned, free floating, flexible, balloon, an electrically conductive,

collapsible, multiplanar reflector network yieldably secured within saidballoon, the aforementioned network being held in an uncollapsedposition when the balloon is inflated whereby impinging ultra shortmagnetic waves are reflected towards their source.

6. An airborne reflector for ultra short magnetic waves comprising, aninflatable, flexible, free floating balloon having an intake port for 0gas, an electrically conductive, collapsible, net

work yieldably secured within said balloon, said network being threeplane surfaces normal to each other so as to form eight three-sidedsections, the aforementioned network being held in an uncollapsedposition when the balloon is inflated, whereby impinging ultra shortmagnetic waves are reflected towards their source.

LEON CHROMAK.

REFERENCES CITED The following references are of record in the NumberName Date 1,007,405 Wagner et al. Oct. 31, 1911 1 1,031,148 Ranza July2, 1912 1,546,803 Stemberg July 21, 1925 2,027,367 Blair Jan. 14, 19362,151,336 Scharlau Mar. 21, 1939 2,396,112 Morgan Mar. 5, 1946 2,406,302Nelson Aug. 20, 1946 FOREIGN PATENTS Number Country Date 3,773 GreatBritain 1886

